The invention relates to an electric machine with a stator having slots distributed about the circumference, with a tooth arranged between each of the slots, with a winding system having at least one winding phase, wherein each winding phase includes at least one coil group, and each coil group includes at least one first single coil and at least one additional single coil, and all single coils of each coil group are electrically connected in series.
An electric machine of this type, in particular an electric machine implemented as a three-strand permanent-excited synchronous machine, exhibits in operation some torque ripple. Several remedies are known for reducing this torque ripple.
For example, DE 199 61 760 A1 discloses that special winding factors of the winding system arranged in the slots of the stator and having the slots at an angle reduce the torque ripple.
DE 101 14 014 A1 also discloses a permanent-excited three-phase machine with a stator having angled slots receiving the winding system. The special design of the stator and the winding system substantially suppress cogging and the fifth harmonic.
In spite of these conventionally applied measures, there is a need for a further reduction of torque ripple. This is of particular importance if the electric machine is to be manufactured inexpensively.